361 engine wonder

[albert smith anderson]

i have a buddy's 806 motor apart, all the exhaust valves are hitting the pistons, with 2 rocker arms already broke. Could this just be from out of adjustment or something else? He has had it the last four years with not much trouble till last fall when it started getting hot and pinging. Any thoughts are greatly welcomed.
 

[Janicholson]

If they hit the pistons, and there was no repairs done before the issue started, the cam is out of time. Bad gears drive key on crank or camshaft. The only other issue would be near totally gone rod bearings, ( but Not likely) Jim
 

[Heat Houser]

Engine overspeed will "float" the valves and cause them to contact the pistons.
 

[the tractor vet]

Now IF that head was off for a valve job and they did not get the valves protrusion set correctly this will cause this . The 361 is a fussy engine and not for the guy that does not know what he is doing. The next NO NO is adjusting the valves with it running as you adjust them with the engine OFF . Now with out being able to see this engine first hand i really don't know for sure . As for the cam jumping time myself i have never run into this YET , Is it possible ??? never seen it YET . As that is and almost bullet prof engine and not uncommon for them to run well over 10000 hours and know of two that are over 20000 with no rebuild. Mine is coming up on the 10 grand mark and had it's first valve adjustment like 6-7 years ago . so get a BOOK and check the valves for how they set above the head surface as i do not have my books setting next to me as they are out in the truck and my boots are off and i ain't ah going to go out in my slippers in the slop.
 

[Janicholson]

I agree with the Vet. If you are just adjusting the valves, and it was a running engine before, the process for adjusting them is not like a gas engine at all. There is an issue with this type of diesel engine.
To get enough compression for reliable ignition, and efficiency, the piston and head are way close together at tdc. This means that as the piston moves up on the exhaust stroke it basically chases the exhaust valve into the head, with very limited clearance. As it moves down on intake the intake valve chases the piston (again with very limited clearance) improperly adjusted valves will crash the engine. My former comments were directed to an engine not touched by anyone before it made noise. Jim
 

[albert smith anderson]

exhaust valve protrusion is .070, there was no work done to this engine in the last 5 yrs that he has had it, so its has to be worn cam/ timing gears or the exhaust valve adjustment. They are hitting enough to where there is a divit from the center hole of the valve.
 

[pete 23]

I would check that cam for any play in drive keyway or end play. Far as valve adjustment, some guys get mixed up on them as intake is .013 and exh is .025 with every other valve being exhaust starting from front. The 400 series engines, intake is front valve and they may have more experience working on those.